What is an Emotion? Introduction to the volume

“Positive” emotions, which lead to pleasure, such as joy, or “negative” emotions, such as anxiety and sadness, constitute distinctive attributes of the most cephalized animals. These emotions, extending beyond cognitive processes, play a crucial role in facilitating adaptation to both the environment and conspecifics. While humans have a subjective experience of emotions, the behaviors exhibited by certain animals, particularly vertebrates, provide an avenue for objective analysis. This is facilitated by the shared presence of the limbic system, a cerebral structure common to all vertebrates, enabling the observation of shared physiological processes. Presently, emotions are distinctive to living beings, affording an opportunity to juxtapose the enriched animal cognition with the more mechanistic, “cold” cognition of artificial systems. There is no evidence to suggest that it is relevant to consider the “emotions” of an artificial device in the same way they are considered in the realm of living organisms. However, in the future, we can imagine artificial systems of another type, close to living beings, or even built on the basis of the homeostasis principle, and in relation to which the question of emotions can be raised again. The aim of this issue is to describe and analyse, in their respective particularities, human emotions and the emotions of different animal groups. It is composed of 6 review articles that address different aspects of this question: human, animal, normal and pathological emotions, anatomical substrates of emotions, computer simulations.